Reaction pathways and kinetic modeling for phenol gasification in supercritical water

Benzene and dibenzofuran form directly from phenol and account for nearly all phenol consumption during its uncatalyzed gasification in supercritical water at 500-700 C. Experiments with dibenzofuran as the starting reactant generated the same array of products - typically in comparable quantities - as that observed previously with phenol as reactant: H₂, CO, CO ₂, CH₄, 2-phenylphenol, polycyclic aromatic hydrocarbons, char, biphenyl, benzene, and even phenol. When benzene was the reactant, biphenyl was the main product and some H₂ formed. Information about the reaction pathways obtained from these experiments served as the basis for constructing a kinetic model that describes the reaction rates of phenol and its primary and gaseous products in supercritical water. We report Arrhenius parameters, and we analyze the formation and consumption rates for each species as calculated by the model.